The comments are actually great -- even Tog weighs in! It also mentions Frank Lehey, who rewrote the Menu Manager for Mac SE and Mac II.

Jake Smith • 5 years ago This was first implemented by Apple's HID team back in the 80s, specifically Bruce Tognazzini, I believe.

Bruce "Tog" Tognazzini Jake Smith • 5 years ago Yes, I did invent it back in 1986 and it is firmly in the public domain. From what I remember, it was Jim Batson who worked out the math and coded it for the Mac OS. The OS X team later failed to copy the algorithm, so I am happy to see that amazon has resurrected it.

Josh Davenport Jake Smith • 5 years ago I think it was yes. It looks like it was originally implemented by NeXT and then removed by Apple when they bought NeXT. Tog himself talks about what happened here: https://www.asktog.com/columns/022DesignedToGiveFitts.html in the answer to question 6 - "When I specified the Mac hierarchical menu algorthm in the mid-'80s, I called for a buffer zone shaped like a <, so that users could make an increasingly-greater error as they neared the hierarchical without fear of jumping to an unwanted menu...........Sadly, the NeXT folks, when coming to Apple, copied Windows, rather than the Mac"

markr_7 • 5 years ago Can't comment on the HID team, Bruce, or possibly the many times it was even implemented at Apple, but as a young developer at Apple in the 80s, I remember stopping by Frank Leahy's office as he was tweaking his code to get menus to "work right." I've often recalled the experience because of the time he was spending to get it right, and how the behavior wasn't simple once you started really trying to meet a users expectations. If I remember right it wasn't just the direction, but also time and therefore velocity. For example, you wouldn't want to stick with the wrong menu if the user wasn't really moving with purpose in the direction of the sub-menu.